已知2xayb与﹣7xb﹣3y4是同类项,则ab=____.
鸭梨味甜、香脆,野生梨味酸,但适应性强.将鸭梨的枝条嫁接到野生梨的砧木上,成活后所结果实的果味是( )
Do you have a baseball bat?
Yes,____ ____.